Our new observations show that this picture is incorrect. First, several newly discovered dLHdC stars have higher photospheric temperatures than many RCB stars (Tisserand et al. 2021, submitted). Second, the spectra presented and analyzed here demonstrate that dLHdC stars in general have different values of \(^{16}\) O/\(^{18}\) O than RCB stars (Section REF ). As the surface abundances of dLHdC and RCB stars remain constant throughout their lifetimes [1]}, it is not possible for one class to evolve into another.
